Design And Research Of High-speed Underwater Video Communication System Based On SoftCast

There is a very limited bandwidth and strict power requirement in underwater communication,which brings us a big challenge to satisfy with the requirements of various services for power consumption and spectral efficiency.During all types of different underwater communication data business,image and video are playing a more and more important role,especially in underwater environment exploration,underwater operation,and exploration of underwater sea creatures and resources.The basic underwater communication technology is an indispensable part of an underwater communication system with good performance.The characters of underwater environment determine that sound becames the ideal mediun instead of electromagnetic waves.However,compared with the wireless channel,underwater acoustic channel has more severe signal loss attenuation,narrower bandwidth and more diverse and complex noise.Besise,the Doppler effects and multipath effects are much more serious.On the analysis of the underwater accustic channel,this paper studies the basic underwater communication technology by a underwater communication system based on single-carrier and focuses on the part of frequency offset estimation.The system was verified by a marine experiment.The results show that the system can achieve an average of 1.95%uncoded BER with QPSK modulation at the 1km range and 5.57%with BPSK at the 10km range with the algorithms proposed in this paper at the receiver.Conventional schems of video transmission have two disadvantages:scalability and robustness.And at the multicast scenery,the performance of different users depends on the user with the worst channel condition.Besides,conventional schems have a cliff effects,and are sensitive to noise and lost packets.A novel wireless video broadcasting approach named SoftCast has been proposed,which is a cross-layer design of mobile video that has good scalability and robustness and performs well in resistance to noise and packet loss,which makes SoftCast very suitable for underwater accustic channel environment.This paper proposed a scheme of underwater video communication after the study on basic underwater communication technology,and research and evalution on the principle and performance of SoftCast.The scheme both satisfies the high requirement of bandwith for video transmission and has the performance advantages from the cross-layer design of SoftCast.Compared with conventional methods,the simulations results show the obvious advantages in resistance to noise and packet loss.